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From: Christophe Leroy <christophe.leroy@csgroup.eu>
To: Benjamin Herrenschmidt <benh@kernel.crashing.org>,
	Paul Mackerras <paulus@samba.org>,
	Michael Ellerman <mpe@ellerman.id.au>,
	npiggin@gmail.com
Cc: linux-kernel@vger.kernel.org, linuxppc-dev@lists.ozlabs.org
Subject: [PATCH v3 02/41] powerpc/40x: Don't use SPRN_SPRG_SCRATCH0/1 in TLB miss handlers
Date: Fri, 12 Mar 2021 12:50:11 +0000 (UTC)	[thread overview]
Message-ID: <4cdaa85d38e14d594ba902424060ec55babf2c42.1615552866.git.christophe.leroy@csgroup.eu> (raw)
In-Reply-To: <cover.1615552866.git.christophe.leroy@csgroup.eu>

SPRN_SPRG_SCRATCH5 is used to save SPRN_PID.
SPRN_SPRG_SCRATCH6 is already available.

SPRN_PID is only 8 bits. We have r12 that contains CR.
We only need to preserve CR0, so we have space available in r12
to save PID.

Keep PID in r12 and free up SPRN_SPRG_SCRATCH5.

Then In TLB miss handlers, instead of using SPRN_SPRG_SCRATCH0 and
SPRN_SPRG_SCRATCH1, use SPRN_SPRG_SCRATCH5 and SPRN_SPRG_SCRATCH6
to avoid future conflicts with normal exception prologs.

Signed-off-by: Christophe Leroy <christophe.leroy@csgroup.eu>
---
 arch/powerpc/kernel/head_40x.S | 39 ++++++++++++++++------------------
 1 file changed, 18 insertions(+), 21 deletions(-)

diff --git a/arch/powerpc/kernel/head_40x.S b/arch/powerpc/kernel/head_40x.S
index 24724a7dad49..383238a98f77 100644
--- a/arch/powerpc/kernel/head_40x.S
+++ b/arch/powerpc/kernel/head_40x.S
@@ -249,13 +249,13 @@ _ENTRY(saved_ksp_limit)
  * load TLB entries from the page table if they exist.
  */
 	START_EXCEPTION(0x1100,	DTLBMiss)
-	mtspr	SPRN_SPRG_SCRATCH0, r10 /* Save some working registers */
-	mtspr	SPRN_SPRG_SCRATCH1, r11
+	mtspr	SPRN_SPRG_SCRATCH5, r10 /* Save some working registers */
+	mtspr	SPRN_SPRG_SCRATCH6, r11
 	mtspr	SPRN_SPRG_SCRATCH3, r12
 	mtspr	SPRN_SPRG_SCRATCH4, r9
 	mfcr	r12
 	mfspr	r9, SPRN_PID
-	mtspr	SPRN_SPRG_SCRATCH5, r9
+	rlwimi	r12, r9, 0, 0xff
 	mfspr	r10, SPRN_DEAR		/* Get faulting address */
 
 	/* If we are faulting a kernel address, we have to use the
@@ -316,13 +316,12 @@ _ENTRY(saved_ksp_limit)
 	/* The bailout.  Restore registers to pre-exception conditions
 	 * and call the heavyweights to help us out.
 	 */
-	mfspr	r9, SPRN_SPRG_SCRATCH5
-	mtspr	SPRN_PID, r9
-	mtcr	r12
+	mtspr	SPRN_PID, r12
+	mtcrf	0x80, r12
 	mfspr	r9, SPRN_SPRG_SCRATCH4
 	mfspr	r12, SPRN_SPRG_SCRATCH3
-	mfspr	r11, SPRN_SPRG_SCRATCH1
-	mfspr	r10, SPRN_SPRG_SCRATCH0
+	mfspr	r11, SPRN_SPRG_SCRATCH6
+	mfspr	r10, SPRN_SPRG_SCRATCH5
 	b	DataStorage
 
 /* 0x1200 - Instruction TLB Miss Exception
@@ -330,13 +329,13 @@ _ENTRY(saved_ksp_limit)
  * registers and bailout to a different point.
  */
 	START_EXCEPTION(0x1200,	ITLBMiss)
-	mtspr	SPRN_SPRG_SCRATCH0, r10	 /* Save some working registers */
-	mtspr	SPRN_SPRG_SCRATCH1, r11
+	mtspr	SPRN_SPRG_SCRATCH5, r10	 /* Save some working registers */
+	mtspr	SPRN_SPRG_SCRATCH6, r11
 	mtspr	SPRN_SPRG_SCRATCH3, r12
 	mtspr	SPRN_SPRG_SCRATCH4, r9
 	mfcr	r12
 	mfspr	r9, SPRN_PID
-	mtspr	SPRN_SPRG_SCRATCH5, r9
+	rlwimi	r12, r9, 0, 0xff
 	mfspr	r10, SPRN_SRR0		/* Get faulting address */
 
 	/* If we are faulting a kernel address, we have to use the
@@ -397,13 +396,12 @@ _ENTRY(saved_ksp_limit)
 	/* The bailout.  Restore registers to pre-exception conditions
 	 * and call the heavyweights to help us out.
 	 */
-	mfspr	r9, SPRN_SPRG_SCRATCH5
-	mtspr	SPRN_PID, r9
-	mtcr	r12
+	mtspr	SPRN_PID, r12
+	mtcrf	0x80, r12
 	mfspr	r9, SPRN_SPRG_SCRATCH4
 	mfspr	r12, SPRN_SPRG_SCRATCH3
-	mfspr	r11, SPRN_SPRG_SCRATCH1
-	mfspr	r10, SPRN_SPRG_SCRATCH0
+	mfspr	r11, SPRN_SPRG_SCRATCH6
+	mfspr	r10, SPRN_SPRG_SCRATCH5
 	b	InstructionAccess
 
 	EXCEPTION(0x1300, Trap_13, unknown_exception, EXC_XFER_STD)
@@ -543,13 +541,12 @@ finish_tlb_load:
 
 	/* Done...restore registers and get out of here.
 	*/
-	mfspr	r9, SPRN_SPRG_SCRATCH5
-	mtspr	SPRN_PID, r9
-	mtcr	r12
+	mtspr	SPRN_PID, r12
+	mtcrf	0x80, r12
 	mfspr	r9, SPRN_SPRG_SCRATCH4
 	mfspr	r12, SPRN_SPRG_SCRATCH3
-	mfspr	r11, SPRN_SPRG_SCRATCH1
-	mfspr	r10, SPRN_SPRG_SCRATCH0
+	mfspr	r11, SPRN_SPRG_SCRATCH6
+	mfspr	r10, SPRN_SPRG_SCRATCH5
 	rfi			/* Should sync shadow TLBs */
 	b	.		/* prevent prefetch past rfi */
 
-- 
2.25.0


  parent reply	other threads:[~2021-03-12 12:51 UTC|newest]

Thread overview: 53+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-03-12 12:50 [PATCH v3 00/41] powerpc/32: Switch to interrupt entry/exit in C Christophe Leroy
2021-03-12 12:50 ` [PATCH v3 01/41] powerpc/traps: Declare unrecoverable_exception() as __noreturn Christophe Leroy
2021-03-12 12:50 ` Christophe Leroy [this message]
2021-03-12 12:50 ` [PATCH v3 03/41] powerpc/40x: Change CRITICAL_EXCEPTION_PROLOG macro to a gas macro Christophe Leroy
2021-03-12 12:50 ` [PATCH v3 04/41] powerpc/40x: Save SRR0/SRR1 and r10/r11 earlier in critical exception Christophe Leroy
2021-03-12 12:50 ` [PATCH v3 05/41] powerpc/40x: Reorder a few instructions in critical exception prolog Christophe Leroy
2021-03-12 12:50 ` [PATCH v3 06/41] powerpc/40x: Prepare for enabling MMU " Christophe Leroy
2021-03-12 12:50 ` [PATCH v3 07/41] powerpc/40x: Prepare normal exception handler for enabling MMU early Christophe Leroy
2021-03-12 12:50 ` [PATCH v3 08/41] powerpc/32: Reconcile interrupts in C Christophe Leroy
2021-03-12 12:50 ` [PATCH v3 09/41] powerpc/32: Entry cpu time accounting " Christophe Leroy
2021-03-12 12:50 ` [PATCH v3 10/41] powerpc/32: Handle bookE debugging in C in exception entry Christophe Leroy
2021-03-12 12:50 ` [PATCH v3 11/41] powerpc/32: Use fast instruction to set MSR RI in exception prolog on 8xx Christophe Leroy
2021-03-12 12:50 ` [PATCH v3 12/41] powerpc/32: Remove ksp_limit Christophe Leroy
2021-03-12 12:50 ` [PATCH v3 13/41] powerpc/32: Always enable data translation in exception prolog Christophe Leroy
2021-03-12 12:50 ` [PATCH v3 14/41] powerpc/32: Tag DAR in EXCEPTION_PROLOG_2 for the 8xx Christophe Leroy
2021-03-12 12:50 ` [PATCH v3 15/41] powerpc/32: Enable instruction translation at the same time as data translation Christophe Leroy
2021-03-12 12:50 ` [PATCH v3 16/41] powerpc/32: Statically initialise first emergency context Christophe Leroy
2021-03-12 12:50 ` [PATCH v3 17/41] powerpc/32: Add vmap_stack_overflow label inside the macro Christophe Leroy
2021-03-12 12:50 ` [PATCH v3 18/41] powerpc/32: Use START_EXCEPTION() as much as possible Christophe Leroy
2021-03-12 12:50 ` [PATCH v3 19/41] powerpc/32: Move exception prolog code into .text once MMU is back on Christophe Leroy
2021-03-12 12:50 ` [PATCH v3 20/41] powerpc/32: Provide a name to exception prolog continuation in virtual mode Christophe Leroy
2021-03-12 12:50 ` [PATCH v3 21/41] powerpc/32: Refactor booke critical registers saving Christophe Leroy
2021-03-12 12:50 ` [PATCH v3 22/41] powerpc/32: Perform normal function call in exception entry Christophe Leroy
2021-03-12 12:50 ` [PATCH v3 23/41] powerpc/32: Always save non volatile registers on " Christophe Leroy
2021-03-12 12:50 ` [PATCH v3 24/41] powerpc/32: Replace ASM exception exit by C exception exit from ppc64 Christophe Leroy
2021-03-12 12:50 ` [PATCH v3 25/41] powerpc/32: Don't save thread.regs on interrupt entry Christophe Leroy
2021-03-12 12:50 ` [PATCH v3 26/41] powerpc/32: Set regs parameter in r3 in transfer_to_handler Christophe Leroy
2021-03-12 12:50 ` [PATCH v3 27/41] powerpc/32: Call bad_page_fault() from do_page_fault() Christophe Leroy
2021-03-12 12:50 ` [PATCH v3 28/41] powerpc/32: Save trap number on stack in exception prolog Christophe Leroy
2021-03-12 12:50 ` [PATCH v3 29/41] powerpc/32: Add a prepare_transfer_to_handler macro for exception prologs Christophe Leroy
2021-03-12 12:50 ` [PATCH v3 30/41] powerpc/32: Only restore non volatile registers when required Christophe Leroy
2021-03-12 12:50 ` [PATCH v3 31/41] powerpc/32: Dismantle EXC_XFER_STD/LITE/TEMPLATE Christophe Leroy
2021-07-31 10:12   ` Finn Thain
2021-07-31 15:39     ` Christophe Leroy
2021-08-01  1:21       ` Finn Thain
     [not found]         ` <34e52975-4ab9-4eb4-3501-02376e38a27c@yahoo.com>
2021-08-01 23:48           ` Finn Thain
2021-08-02 15:19         ` LEROY Christophe
2021-08-03  0:43           ` Finn Thain
     [not found]           ` <62d36dbb-4b39-f5bd-7962-4dcfbea729b3@linux-m68k.org>
     [not found]             ` <683c8156-97b0-5ba7-ce31-2e8613089836@yahoo.com>
2021-08-04  4:57               ` Finn Thain
2021-07-31 16:40     ` Christophe Leroy
2021-08-01  1:39       ` Finn Thain
2021-03-12 12:50 ` [PATCH v3 32/41] powerpc/32: Remove the xfer parameter in EXCEPTION() macro Christophe Leroy
2021-03-12 12:50 ` [PATCH v3 33/41] powerpc/32: Refactor saving of volatile registers in exception prologs Christophe Leroy
2021-03-12 12:50 ` [PATCH v3 34/41] powerpc/32: Save remaining registers in exception prolog Christophe Leroy
2021-03-12 12:50 ` [PATCH v3 35/41] powerpc/32: Return directly from power_save_ppc32_restore() Christophe Leroy
2021-03-12 12:50 ` [PATCH v3 36/41] powerpc/32: Only use prepare_transfer_to_handler function on book3s/32 and e500 Christophe Leroy
2021-03-12 12:50 ` [PATCH v3 37/41] powerpc/32s: Move KUEP locking/unlocking in C Christophe Leroy
2021-03-27 17:24   ` Christophe Leroy
2021-03-12 12:50 ` [PATCH v3 38/41] powerpc/64s: Make kuap_check_amr() and kuap_get_and_check_amr() generic Christophe Leroy
2021-03-12 12:50 ` [PATCH v3 39/41] powerpc/32s: Create C version of kuap save/restore/check helpers Christophe Leroy
2021-03-12 12:50 ` [PATCH v3 40/41] powerpc/8xx: " Christophe Leroy
2021-03-12 12:50 ` [PATCH v3 41/41] powerpc/32: Manage KUAP in C Christophe Leroy
2021-03-31  1:09 ` [PATCH v3 00/41] powerpc/32: Switch to interrupt entry/exit " Michael Ellerman

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